Surface-traversing vehicle

ABSTRACT

A vehicle for traversing a surface such as for carrying out an inspection, survey or maintenance operation upon that surface comprises two bodies interconnected by means to move the bodies towards and away from each other, each of those bodies being supported upon a multiplicity of resilient bristles ( 13; 25; 32 ) extending from it, the bristles of each body being mounted in groups upon bristle-carrying members ( 10; 23; 31 ) each guided for movement towards and away from the body, and fluid pressure means ( 25; 22; 34 ) to effect the guided movement of the bristle-carrying members in at least one of those directions.

BACKGROUND TO THE INVENTION

1. Field of the Invention

The present invention is a vehicle for traversing a surface such as forcarrying out an inspection, survey or maintenance operation upon thatsurface.

2. Description of Related Art

In Patent Specification No. GB2305407A we have described a vehicle forthis purpose which comprises two bodies interconnected by means to movethe bodies towards and away from each other, each said body beingsupported upon a multiplicity of resilient bristles extending from it.Operation of that vehicle by alternate moving of the bodies towards andaway from each other causes it to move in successive steps along agenerally linear path over the surface upon which it is supported. Thebristles are inclined by a small amount away from being perpendicular tothe surface and thereby provide a grip upon that surface which isgreater in one direction than in the opposite direction, as determinedby the direction of inclination of the bristles.

This foregoing surface-traversing vehicle has proved to be able to moveprogressively and effectively over a range of different surfaces. Whenit is required to move in the opposite direction, for example towithdraw from a tubular conduit in which it has been operating, it isnecessary for the surface-gripping effect of the bristles to be reversedby reversing the direction of inclination of the bristles. One possibleway of achieving that reversal is to rely wholly upon the resiliency ofthe bristles and to reverse their direction of inclination simply bypulling axially upon the relevant bristle-supporting body. Thereorientation of the bristles may be assisted by rotating the relevantbody about its axis.

As indicated in the above patent specification, it could be advantageousif at least one of the bristle-supported bodies were constructed withretractable bristles. However the provision of a mechanically-operatedsystem for retracting such bristles is particularly difficult in thecase of surface-traversing vehicles of the present general type in thatone important use of such vehicles is in the harsh environments ofsewers, oil pipelines and the like, wherein deposited dirt and othersediments can readily impede continued satisfactory mechanicaloperations. It is perhaps not surprising that no satisfactory provisionof such retractable bristles has hitherto been available.

It is therefore an object of the present invention to provide asurface-traversing vehicle of this general type in which a practical andadvantageous retraction of the bristles is made possible.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, there is provided asurface-traversing vehicle comprising a plurality of bodies at least onemoving device for moving at least one pair of adjacent said bodiestowards and away from each other, a plurality of bristle-carryingmembers mounted to a plurality of said bodies, a plurality of resilientbristles mounted to each said bristle-carrying member, wherein each saidbristle-carrying member is adapted to be moved in a respective firstdirection away from the corresponding said body and a respective seconddirection towards the corresponding said body, and at least one fluidpressure device for moving said bristle carrying members in therespective first and/or second direction thereof relative to thecorresponding said body, wherein said moving device is adapted to causesaid vehicle to traverse a surface by moving at least one pair ofadjacent said bodies towards and away from each other when a pluralityof said bristles of said body are in engagement with said surface tosupport the vehicle.

Thus, by operation of the fluid pressure means associated with one ofthe bodies, the bristles of that body may be retracted and/or extendedas required, to enable their orientation to be reversed and the body tobe moved more readily in its reverse direction, thereby permittingreversal of the direction of movement of the surface-traversing vehicle.

As described in Specification No. GB2305407A, the interconnected bodieswhich are a feature of the surface-traversing vehicles of the type towhich the present invention is applied may be of various shapesdepending upon the general nature of the surface to be traversed. Thusthey may be generally flat or, for example, rotationally symmetrical,for example generally cylindrical. The bristles may extend generallyperpendicularly from the bodies if the bodies are flat. Most usually,the bodies will be generally cylindrical and the bristles will extendgenerally radially outwardly or inwardly of the body. While thesurface-traversing vehicle may comprise generally hollow bodies withinwardly-directed bristles, designed to enable it to progress over theouter surface of a chimney, cable or like conduit, the vehicle isparticularly well adapted to use within a tubular pipe, sewer or similarconduit and for that purpose will have outwardly-directed bristles, inparticular bristles directed radially outwardly.

Although in most cases the bristles are preferably directed generallyperpendicularly, including radially, from the bodies upon which they aremounted, in particular when the bodies are viewed from the side relativeto their direction of relative movement, when those bodies arerotationally symmetrical, the bristles may be inclined to a small extentin the rotational direction in order to discourage undesired rotation ofthe bodies. For example, alternate bristles or groups of bristles aroundthe bodies may be inclined in alternate directions in a cross-plystructure to stabilize the bodies against such rotation.

The bristles of each of the bodies are mounted in groups upon aplurality of bristle-carrying members each guided for movement towardsand away from the said body. These bristle-carrying members may bespaced apart at intervals over the surface of the body but preferablythey combine to cover the whole of the relevant surface of the body andtherefore lie closely together at one limit of their guided movement. Byway of example, in the case of generally cylindrical bodies havingoutwardly-directed bristles, the bristle-carrying members may each formone angular segment of the cylindrical surface of the body. Preferablysuch segments are all of equal angular size, for example 4, 6 or 8segments each covering, respectively, 90 degrees, 60 degrees or 45degrees of the cylindrical surface of the body.

The bristle-carrying members are guided so that they may move towardsand away from the body upon which they are mounted. Preferably thatmovement is generally radial with respect to the axis of a generallycylindrical body. To that general end, the axially opposite ends of eachbristle-carrying member may be designed to engage generally radial slotsor guide channels in the ends of the body. As an alternative, thebristle-carrying members may be mounted upon pins extending throughradial apertures or bores in the body, or may themselves slide uponradial pins upon the body.

The movement of the bristle-carrying members towards and/or away fromthe associated bodies is effected by a fluid pressure means. It ispreferred that the latter means be hydraulically, or more preferablypneumatically, operated. By way of example, when the bristle-carryingmembers each form an angular segment of the body, a membrane, forexample a generally cylindrical tubular bag-shaped membrane, may belocated along the axis of the body in contact with the radially innerfaces of the members. When the membrane is caused to expand outwardly,either by stretching or by unfolding, upon the introduction of, say,compressed air into its interior, the bristle-carrying members arethereby urged outwardly. The latter members may subsequently disengagefrom the surface being traversed either simply in response to theabsence of radially outward pressure or, more positively, under theaction of one or more return springs when the fluid pressure is removed.

In one alternative form of the surface-traversing vehicle according tothe present invention, the bristle-carrying members are each supportedupon a plurality of inwardly-directed pistons, each arranged to slide,in response to fluid pressure on their inner ends, outwardly withinradial, fluid-tight bores within the associated body. The returnmovement of the bristle-carrying members may, for example, be inresponse to evacuation of the bores and/or by the action of one or moresprings and/or by the resilient action of the bristles themselves.

In yet another form of the vehicle of the present invention, inparticular for use in restricted spaces such as within narrow-borepipes, the bristles may be mounted directly upon pistons, that is, thebristle-carrying members are then themselves in the form of pistons.Typically, such bristle-carrying pistons are moved by means of amembrane, preferably a generally tubular membrane such as in the form ofa thin-walled bag.

Whatever the form of the fluid pressure means by which the movement ofthe bristle-carrying members is effected, it is advantageous to providealso a resilient means tending to resist that movement of thebristle-carrying members. In this way, by varying the pressure of thefluid pressure means, the bristle-carrying members may be set in aselected position intermediate to their fully-retracted and theirfully-extended positions. This enables the bristles to be inclined to agreater or lesser extent to take account of variations in the surfacebeing traversed by the vehicle. By way of example, if the frictionalvalue of the surface changes in response to variations in the surfaceroughness or as a result of the presence of a lubricant on the surface,the inclination of the bristles may be modified to maintain the desiredlevel of grip of the body upon the surface. Similarly, when the vehicleis being used to traverse the interior surface of a hollow conduit, forexample of a pipe, the amount by which the bristle-carrying bodies areextended may be modified in this way to compensate for variations in theinternal cross-sectional dimensions of the conduit.

Such a resilient means to resist the movement of the bristle-carryingmembers may take various forms, including for example that of one ormore springs, e.g. coil springs. In one form, the resilient meanscomprises one or more pieces of a resilient polymeric material, forexample an annular piece surrounding an end of the bristle-carryingbodies or one such piece at each end thereof. The polymeric material mayfor example be of a resilient polyurethane or a natural or syntheticrubber.

When the surface-traversing vehicle according to the present inventionincludes bristle-carrying members whose degree of extension can bevaried as described above, it is advantageous and preferred to provideone or more sensors to monitor the characteristics of the surface, forexample pipe diameter and/or surface roughness, ahead of the vehicle, sothat the fluid pressure within each body, and thereby the degree ofextension of the bristles, may be modified to take account of anyvariations in the surface characteristics as the vehicle encounters suchvariations. The fluid pressure may be modified by the person operatingthe vehicle or, advantageously, using some form of automatic“intelligent” controller.

The resilient bristles may be of any material having the selectedresiliency and may be chosen to reflect the circumstances in which thevehicle is to operate including, among other factors, the load to besupported and/or towed by the vehicle. Thus they may be natural bristlesor they may be of a synthetic polymeric material, for example, or of ametal. The selected material preferably has a relatively high stiffnessand a good elasticity. It is particularly preferred to use metalbristles, for example of steel, in view of the quick elastic response,and the usually better surface grip, of such metal bristles. Because, byvirtue of the present invention, any required reversal of the directionof inclination of the bristles is greatly aided by the retraction of thebristles, bristles of higher stiffness may be used than would bepossible if they had to be re-directed without retraction.

The vehicle moves over the surface in response to the movement of thebodies towards and away from each other. This relative movement of thebodies may be achieved by any desired means, for example by electricalpower provided by an on-board source such as a rechargeable battery orby a remote source via an electrical line. However it is particularlypreferred to effect relative movement of the bodies by fluid pressure,in particular by linking the bodies by a hydraulic or more preferablypneumatic cylinder.

Additional support for the bodies may be provided in the form of one ormore wheels, whereby the load borne by the bristles is reduced. Suchwheels may be located upon the bodies themselves or upon the linksbetween them, for example.

In one advantageous form of the invention, wheels may be mounteddirectly upon one or more of the bristle-carrying members. In this way,the distance, or the minimum distance, of the bristle-carrying membersfrom the surface under treatment may be set at an advantageouspredetermined value, for example a value at which the inclination of thebristles relative to the surface is optimized.

While the surface-traversing vehicle according to the invention maycomprise just two of the bristle-supported bodies, it may proveadvantageous to provide three or more such bodies. For example, reversalof the direction of operation of the vehicle may be assisted by theprovision of a third body and/or the movement of the vehicle overall maybe rendered more smooth in this way. In one arrangement, the bodies maybe coupled together in pairs, with the two bodies in each pair beingcoupled at a fixed distance apart, thereby increasing the effectivelength of each body.

Particularly when the vehicle comprises at least three of thebristle-supported bodies, it is desirable that the required relativemovement of the bodies be effected automatically, for example by meansof a suitable controller, which may be located either upon the vehicleor at a remote location, to which latter the vehicle may be linked by adirect line or by radio.

When the vehicle is designed to be operated pneumatically, an air linemay be provided from a remote source of compressed air to the pneumaticcylinders. That line may be combined with an electrical line, in theform of an umbilical linking a remote control position to the vehicle.The umbilical may in turn be dragged behind the vehicle by means of asimilar towing vehicle specifically provided for that purpose. As thevehicle proper moves further from the control position, supplementarysuch umbilical tugs may be added. Sensors in the line may monitortension in the umbilical and in turn prompt an umbilical tug to respondby accelerating or decelerating briefly.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The invention will now be further described with reference to theaccompanying drawings, which illustrate, by way of example only, threealternative preferred forms of the bristle-supported bodies of thesurface-traversing vehicle according to the present invention andwherein:

FIG. 1 is a transverse sectional view of a first embodiment of abristle-supported body, with the bristles retracted;

FIG. 2 is an elevation from one end of the body of FIG. 1, with thebristles extended;

FIG. 3 is a transverse sectional view of a second embodiment ofbristle-supported body, with the bristles extended;

FIG. 4 is a longitudinal sectional view of one end of the embodiment ofFIG. 3, with the bristle-carrying bodies extended.

FIG. 5 is a transverse sectional view of a third embodiment of abristle-supported body, with the bristles extended;

FIG. 6 is a view corresponding to that of FIG. 5, with the bristlesretracted;

FIG. 7 is a view corresponding to FIG. 5 of a fourth embodiment of abristle supporting body, with the bristles thereof extended; and

FIG. 8 is a side view of a surface traversing vehicle incorporatingfeatures shown in FIGS. 1 to 7.

FURTHER DETAILED DESCRIPTION OF THE INVENTION

The body illustrated in FIGS. 1 and 2 is of cylindrical form and isconstructed from six bristle-carrying members 10, each forming onesector of the cross-section of the cylinder. The members 10 are shown assolid but may be of a more open construction in order to limit theirweight. The members 10 are mounted together between disc-shapedend-plates 11 and each member engages a guide slot 12 at each of itsends, which guide slots permit the members 10 to move by a limitedamount radially outwardly relative to the axis of the body. Each of themembers 10 carries a large number of bristles 13 distributed throughoutthe length of its outer curved surface.

Located within a central bore 14 and extending throughout the length ofthat bore is a generally cylindrical, tubular bag-shaped membrane 15,made of a stretchable rubber material. The membrane 15 may be expandedby the introduction of air under pressure into the interior of thetubular membrane and, in expanding, it drives the bristle-carryingmembers 10 outwardly, their movement being constrained to a radial pathby the guide slots 12. In one form of the invention, the membrane 15 isencircled by a strong restraining sheath, for example of metal foil (notshown), to prevent the membrane entering the gaps which are formedbetween the members 10 as they move outwardly.

Thus an increase of air pressure within the membrane 15 causes thebristles to move into engagement with the inner wall of a conduit or thelike (not shown) within which the vehicle is located and thereby to gripthat wall and allow the vehicle to progress along the conduit in themanner described above. Spring means (not shown) may be provided toassist the inward return of the members 10, and thereby retraction ofthe bristles 13, on removal of the air pressure within the membrane 15.Retraction of the bristles in this way allows the bristle-supported bodyto be moved axially to redirect the inclination of the bristles.

The form of the bristle-supported body illustrated in FIG. 3 comprises atubular aluminium cylinder 20 pierced throughout its length by a numberof air-tight bores 21. The bores 21 are distributed in staggered pairsalong the length of the cylinder. Within each bore 21, a piston-type pin22 is slidable. Each of four aligned series of pins 22 supports anelongated bristle-carrying member 23, of arcuate cross-section. Themembers 23 engage each other to combine to form a cylindrical outer faceto the body when they are slid radially inwardly to the maximum extent.

Each pin 22 carries an integral disc-shaped plate 24 at its inner end.The staggering of the bores 21 as illustrated allows the pins 22 to movetowards their radially most inward positions without mutualinterference.

Because the bores 21 are air tight, an increase of air pressure withinthe cylinder 20, acting upon the plates 24, causes the pins 21 to moveradially outwardly and in turn to move the members 23, and bristles 25carried by them, to their outermost positions as shown. In thisposition, the bristles may engage the inside face of a generally tubularconduit. When it is desired to retract the bristles out of engagementwith the surface which is being traversed by the vehicle, the pins 22are withdrawn radially inwardly by a reduction of the air pressurewithin the cylinder 20. The retraction of the members 23 in this waymay, if desired, be aided by springs provided to act upon the pins 22and/or by the natural resilience of the bristles 25.

The bristle-supported body of which one end is illustrated in FIG. 4 isclosely similar to that of FIG. 3 and like numerals are used to identifylike parts. However at each end of the body, a resilient annular“spring” 28 of polyurethane encircles the bristle-carrying members 23between the outer surface of those members and a flange 26 projectingfrom the end-plate 27.

The body of FIG. 4 is illustrated in the condition in which the bristles25 are extended to a maximum extent and in which therefore the spring 28is fully compressed. However if the air pressure within the cylinder 20is set at a lower level, then the resilience of the spring 28 urges themembers 23 radially inwardly until a balance is reached between the airpressure within the cylinder 20 acting upon the pressure plates 24 andthe inwardly-directed pressure of the spring. Thus the degree to whichthe members 23 and bristles 25 are extended radially outwardly can beset at any time by varying the air pressure in the cylinder 20. In thisway, the bristles can be inclined against the inner face of a conduit inwhich the bristle-supported body is located, to an angle of inclinationappropriate to the internal diameter of the conduit and to thefrictional characteristics of the inner surfaces of the conduit. Thatangle of inclination can subsequently be varied readily by increasing orreducing the air pressure to the necessary extent.

Referring now to FIGS. 5 and 6, the bristle-supported body 30 thereillustrated is of particular value, but not exclusively, for use in atubular conduit of a relatively small diameter, for example of the orderof 5 to 15 cm. Piston-shaped ferrules 31, each of which supports anumber of bristles 32, extend radially through the body 30 and are freeto move by a short radial distance relative to the body. In theillustrated form of the invention, the ferrules are mounted insymmetrical groups of three, alternate groups being staggered angularlyalong the length of the body 30. Referring to FIG. 7, an embodiment ofthe invention in which the bristles 32 form a cross-ply structure isshown.

The inner ends of the ferrules 31 are in the form of flat plates 33 and,within the body 30 and designed to apply an outward radial force uponthe plates 33, is an air bag 34. As shown in FIG. 5, when the air bag 34is inflated, the bristles are driven outwardly to enable them to engagethe inner surface of a cylindrical conduit (not shown) in which the body30 is disposed.

When the air bag 34 is subsequently evacuated and thereby collapsedinwardly as shown in FIG. 6, the ferrules 31 return inwardly into thebody 30 by virtue of the resilience of the bristles 32 and the bristlesare thereby retracted, to enable the surface-traversing vehicle to bemoved axially, for example to reverse the direction of inclination ofthe bristles relative to the surface being traversed.

Finally, referring to FIG. 8, a surface traversing vehicle having threebristle supporting bodies 30, connected by a series of linkages 40 isshown. The vehicle has a power supply umbilical 42 and a front-endsensor 44. The vehicle is supported on a plurality of wheels 48. Thevehicle is controlled by a control unit 50 and has a hydraulic cylinder52 used to inflate and deflate the air bags (not shown).

What is claimed is:
 1. A surface-traversing vehicle comprising aplurality of bodies, at least one moving device for moving at least onepair of adjacent said bodies generally axially towards and away fromeach other, a plurality of bristle-carrying members mounted on each ofat least two of said plurality of bodies, a plurality of resilientbristles mounted to each said bristle-carrying member, wherein each saidbristle-carrying member is adapted to be moved in a respective firstdirection that has a radical component away from the body to witch it ismounted and a respective second direction towards the body to witch itis mounted. and at least one fluid pressure device for moving each saidbristle carrying member in at least a first direction relative to thebody to witch it is mounted, wherein said moving device is adapted tocauses said vehicle to traverse a surface by moving at least one pair ofadjacent said bodies towards and away from each other when a pluralityof said bristles of said body are in engagement with the surface tosupport the vehicle.
 2. A surface-traversing vehicle according to claim1, wherein a plurality of said bodies are substantially flat or arerotationally symmetrical.
 3. A surface-traversing vehicle according toclaim 2, wherein alternate bristles or groups of bristles around saidbodies are inclined to a small extent in alternate directions in therotational direction of said bodies.
 4. A surface-traversing vehicleaccording to claim 1, wherein a plurality of said bodies aresubstantially cylindrical and said bristles extend substantiallyradially outwardly or inwardly of the corresponding said body.
 5. Asurface-traversing vehicle according to claim 1, wherein a plurality ofsaid bristle-carrying members combine to substantially cover a surfaceof at least one said body at one limit of movement of saidbristle-carrying member relative to said body.
 6. A surface-traversingvehicle according to claim 5, wherein said bristle-carrying members eachform one angular segment of the surface of a substantially cylindricalbody.
 7. A surface-traversing vehicle according to claim 1, wherein themovement of said bristle-carrying members is guided by slots, guidechannels, apertures or bores in the corresponding said body or by radialpins upon the corresponding said body.
 8. A surface-traversing vehicleaccording to claim 1, wherein at least one of said at least one fluidpressure device comprises a membrane in contact with the inner faces ofthe corresponding said bristle-carrying members.
 9. A surface-traversingvehicle according to claim 1, wherein at least one of said at least onefluid pressure device comprises a plurality of pistons arranged to slidein fluid-tight bores within the associated body.
 10. Asurface-traversing vehicle according to claim 9, wherein saidbristle-carrying members are themselves in the form of said pistons. 11.A surface-traversing vehicle according to claim 1, further comprising atleast one resilient member tending to resist movement of a respectivesaid bristle-carrying member relative to the corresponding said body.12. A surface-traversing vehicle according to claim 11, wherein said atleast one resilient member comprises one or more springs.
 13. Asurface-traversing vehicle according to claim 1, further comprising oneor more sensors to monitor the characteristics of the surface ahead ofthe vehicle.
 14. A surface-traversing vehicle according to claim 1,wherein said resilient bristles are natural bristles or formed of asynthetic polymeric material or of a metal.
 15. A surface-traversingvehicle according to claim 14, wherein said resilient bristles are ofsteel.
 16. A surface-traversing vehicle according to claim 1, wherein atleast one of said at least one moving device is adapted to useelectrical power.
 17. A surface-traversing vehicle according to claim 1,wherein at least one of said at least one moving device is adapted touse fluid pressure.
 18. A surface-traversing vehicle according to claim17, wherein a plurality of said bodies are linked by at least onehydraulic or pneumatic cylinder.
 19. A surface-traversing vehicleaccording to claim 1, wherein said bodies are further supported by oneor more wheels, located upon said bodies or upon the links between themor upon one or more of the bristle-carrying members.
 20. Asurface-traversing vehicle according to claim 1, comprising three ormore said bodies.
 21. A surface-traversing vehicle according to claim20, wherein the bodies are coupled together in pairs, the two bodies ineach pair being at a fixed distance apart.
 22. A surface-traversingvehicle according to claim 21, further comprising at least one controldevice to effect automatically relative movement of the bodies.
 23. Asurface-traversing vehicle according to claim 21, adapted to be operatedfrom a remote position via an umbilical line towed by a similar towingvehicle.
 24. A self-propelled surface-traversing vehicle, comprising atleast a first body and a second body, said first and second bodies beingoperatively-connected and each comprising at least one bristle-carryingmember having a plurality of resilient bristles, wherein said vehiclecan be propelled along a surface by a generally axial movement of saidfirst and second bodies towards and away from each other when aplurality of said bristles are engaged with the surface, at least saidfirst body further comprising a hydraulic or pneumatic moving mechanismfor radially moving at least one of said bristle-carrying members withrespect to said first body.
 25. The surface-traversing vehicle of claim24, wherein said second body further comprises a hydraulic or pneumaticmoving mechanism for radially moving at least one of saidbristle-carrying members with respect to said first body.
 26. Thesurface-traversing vehicle of claim 25, wherein said moving mechanism ispneumatic.
 27. The surface-traversing vehicle of claim 24, wherein saidmoving mechanism is pneumatic.